Ecological Assessment of Coastal Wetlands in Oguta Lake Area, Imo State

Coastal and freshwater wetlands in South East Nigeria represent ecologically rich habitats that provide provisioning, regulating, and cultural services to local communities. This study conducted an ecological assessment of the wetland habitats surrounding Oguta Lake in Imo State, South East Nigeria. Field assessments were conducted during wet and dry seasons, covering vegetation surveys, water quality measurements, benthic invertebrate sampling, and direct community consultations. Vegetation surveys were carried out using stratified random quadrats to determine species composition, density, and diversity of aquatic and semi-aquatic plant communities. Benthic invertebrates were sampled using an Ekman grab at five lake margin stations. Water quality was assessed using in situ probes and laboratory analysis. Six major wetland habitat types were identified: floating macrophyte beds, submerged aquatic vegetation zones, emergent vegetation stands, inundated forest patches, open water areas, and riparian grasslands. Nymphaea lotus and Pistia stratiotes dominated floating macrophyte communities. Benthic invertebrate diversity was highest in emergent vegetation zones and lowest in open-water mud habitats. Water quality was within acceptable limits at most stations, with the exception of elevated turbidity and BOD at the inlet station. Interview data revealed high community dependence on wetland resources for fishing, weaving, medicinal plants, and water supply. Anthropogenic threats including drainage for agriculture and illegal sand excavation were documented at all sites. A wetland ecological sensitivity map was produced as a planning tool for the Imo State government. Keywords: wetland ecology, Oguta Lake, aquatic vegetation, benthic invertebrates, Imo State.